Pharmacokinetics Of Ceftiofur Hydrochloaride In Chickens

AIM:A method was developed for the quantitative detection of ceftiofur hydrochloaride and its active metabolite DCF in chickens plasma, using reversed-phase high performance liquid chromatography (RP-HPLC) and the extraction and purification from the plasma and tissues of chickens, and study bioavailability of ceftiofur hydrochloaride in plasma after oral administration and intravenous in chickens , in order to gain the precise pharmacokinetics parameters and bioavailability of ceftiofur hydrolchloaride in chickens , and provide reasonable evidence for veterinary clinical medication, e.g.METHODS: Firstly, the blood samples were collected in heparinized tubles at different intervals after intravenous and oral administration to chickens of ceftiofur hydrochloaride, and centrifuged at 3,000×g for 10 min at room temperature to collect plasma . Secondly , dithioerythritol (DTE) was added to each plasma samples, After vortex mixing, the tubes were placed in a water bath at 50℃for 15 min, at regular time intervals (e.g. each 3 min), the samples were vortex mixed and placed back immediately in the water bath. Thereafter, the samples were cooled down to room temperature and 1.5 ml of the iodoacetamide solution were added. The samples were mixed well and were left in the dark at room temperature for 30 min. Following derivatization, the samples were×transferred to an DIKMA ProElut PLS SPE column (60 mg/3 ml) that was preconditioned with 1ml of methanol and 1ml of water. The sample was allowed to pass slowly through the HLB column. The column was washed with 1ml of a 5% (v/v) solution of methanol in water and dried by applying vacuum for 10 min .Elution was performed using 1ml of a 5% (v/v) solution of acetic acid in acetonitrile . The eluate was concentrated to dryness under a gentle stream of nitrogen at a temperature of±45℃. The dryresidue was dissolved in 500 ₁ of water, vortex mixed for 15 s, and transferred to an autosampler vial. Lastly, the samples were determined by using RP-HPLC after solid-phase extraction and nitrogen dryer adding suitable mobile phase, Chromatographic separation was carried out on a C₁₈ column (250mrm×4.6mm,5μm) with acetonitrile-water-trifluoroacetic acid (300: 700: 1 by volume) as mobile phase at a flow rate of 1mL/min, followed by determination of the residue by ultraviolet absorption detector at 266 nm. The concentration-time data of DCF in plasma were analyzed with 3P97 pharmacokinetics program and the bioavailability was calculated by dose calibration method.RESULTS: The correlation of calibration curve were all good, which correlation coefficient were more than 0.990. The limit of detection (LOD) was 0.05μg·mL^-1, 0.10μg/g, 0.10μg/g, 0.10μg/g in plasma, lung, liver and kidney, respectively. The average extraction recovery was more than 80% from the tissues and plasma. The intra-day coefficient of variations and inter-day coefficient of variations were less than 10% and 15% respectively. The chickens received intravenous and oral administration of ceftiofur hydrochloaride, The results indicated the plasma drug concentration-time data were fitted two-compartment open models. After intravenous administration (2.5mg/kg·b·w), the disposition half-life (t_1/2α) of the drug was 0.70±0.38h, whereas the elimination half-life (t_1/2β) of the drug was 0.61±0.56h. The area under the plasma concentration-time curve (AUC) was 30.98±6.40 (μg/ mL)·h. The total body clearance (CL_b) was 0.08±0.03 L/(kgh). The apparent distribution volume (V_d) was 0.18±0.05 L/kg. After oral administration (2.5mg/kg·b·w), the disposition half-life (t_1/2α) of the drug was 2.46±0.52h, whereas the elimination half-life (t_1/2β) of the drug was 7.60±1.78h. The area under the plasma concentration-time curve (AUC) was 14.03±2.54 (μg/mL)·h. The total clearance of ceftiofur hydrochloaride (CL_b) was estimated to be 0.13±0.06 L/(kg·h). The time-point of maximum plasma concentration of the drug (T_max) and the maximum plasma concentration (C_max) were calculated as 1.28±0.46h and 2.57±0.43μg/mL. The bioavailability was 47.53±3.25%.